1. The Field of the Invention
The invention generally relates to providing an interface module for connecting communication components with different communication protocols. More specifically the invention relates to an interface module for connecting, for example, a legacy 300 pin 10 Gigabit, sixteen-bit interface (XSBI) or a or Serializer/Deserializer Framer Interface-4 (SFI-4) system with an optical transceiver module having a different interface.
2. Description of the Related Art
In the field of data transmission, one method of efficiently transporting data is through the use of fiber optics. Digital data is propagated through a fiber optic cable using light emitting diodes or lasers. Light signals allow for extremely high transmission rates and very high bandwidth capabilities. Also, light signals are resistant to electromagnetic interference that would otherwise interfere with electrical signals. Light signals are more secure because they do not allow portions of the signal to escape from the optical fiber as can occur with electrical signals in wire-based systems. While there may be an evanescent field that enables one to siphon some portion of the light off the fiber by bending the fiber such that it is possible to tap fiber communications without breaking the fiber, it is in general much more difficult than for electrical communications. Light also can be conducted over greater distances without the signal loss typically associated with electrical signals on copper wire.
Although fiber optic networks exhibit the desirable characteristics described above, there continues to exist a need for using other types of communication devices. For example, most computers or other electronic devices that communicate using optical networks are electrical, and conduct electrical signals over electrically conductive materials. Additionally, in the networking context, electrical networks that transmit electrical signals continue to be widespread. For these and other reasons, optical networks typically include optical transceivers that represent interfaces between electrical components and optical portions of the network.
One particular electrical conducting based protocol and physical construction is based on the 300 pin standard. The 300 pin standard refers in one aspect to the physical construction for a connector layout for interfacing with other 300 pin devices and system. The communication interfaces associated with the 300 pin standard include the Serializer/Deserializer Framer Interface-4 (SFI-4) of the Optical Internetworking Forum (OIF) and the derivative 10 Gigabit, Sixteen-Bit Interface (XSBI) of the 10 Gigabit Ethernet Alliance. The XSBI standard is the interface used in conjunction with the 10-Gigabit Ethernet standard. The SFI-4 standard is the interface associated with the SONET (Synchronous Optical Network) protocol. Components using these two interfaces are generally cross compatible, such that a component designed for one of the interfaces can also function with the other interface standard. The 300 pin architecture has several drawbacks, including a fragmented protocol, physical connectors that are mechanically unreliable, and associated z-mount devices that are not hot-pluggable. In spite of these drawbacks, the 300 pin architecture has enjoyed significant market penetration, and there are a substantial number of 300 pin standard devices in existing 300 pin systems. There has, therefore, been a movement to interface systems based on the 300 pin architecture with devices having other interfaces that are easier and more user friendly in their implementation.
One prior art example of a device used to interface 300 pin system to a fiber optic network is shown in FIG. 1, which illustrates an optical transceiver module designated generally as 100, and otherwise known as an XBI module. Also shown in FIG. 1 is a 300 pin physical layer integrated circuit (IC) 102. The 300 pin physical layer IC 102 is connected to a 300 pin mating connector 104 for interfacing with a corresponding 300 pin connector 106 in the optical transceiver module 100.
The 300 pin protocol standard defines a parallel communication link with 16 communication lines in both transmit and receive directions. Each communication line uses a two-wire differential connection, meaning that the 16 transmit lines require thirty-two physical connections to accomplish the parallel transmit communication. The 300 pin receptacle 106 has a 16-line transmit bus 108 that feeds a 16-line parallel data transmission from the 300 pin physical layer IC 102 into a multiplexer 110. The multiplexer 110 converts the parallel data on the transmit bus 108 into a serial high-speed data transmission. This serial high-speed data transmission is sent to a laser diode driver 112. The laser diode driver 112 converts the serial high-speed data transmission into a modulated electrical drive current for driving a laser diode 114. By modulating the laser diode 114, an optical signal is generated and propagated onto a fiber optic network through an optical output port 116.
In the receive path, an optical signal representing a serial high-speed data stream is received by an optical input port 118 on the optical transceiver module 100. The optical signal is focused onto a photodiode 120 that converts the optical signal into electrical pulses. The electrical pulses are sent to a trans-impedance amplifier 122 and a post amplifier 124, the combination of which digitizes the signals into a serial high-speed data stream. The serial high-speed data stream is propagated through a serial connection into a demultiplexer 126. The demultiplexer 126, using an appropriate clock signal 128, converts the serial high-speed data stream into a 16-line parallel data stream that is sent through a 16-line receive bus 130, the 300 pin connector 106, and the 300 pin mating connector 104 to the 300 pin physical layer IC 102. In this manner, a 300 pin standard system is interfaced with a fiber optic network.
Although the interfaces and connectors described above are useful for establishing communication between the 300 pin physical layer IC and the optical network, there are certain disadvantages associated with the optical transceiver module 100 illustrated in FIG. 1. For instance, the optical transceiver module generally has a large form factor and a number of discrete electrical components, such as the multiplexers, demultiplexers, and amplifiers. More integrated optical transceivers with fewer discrete components and a smaller form factor have been developed recently, but such newer optical transceivers have not been compatible with legacy interfaces, such as those associated with the 300 pin connectors and interfaces described above.